Werner states

If I was given a general Werner state: u |001> + v |010> + w |100>, where u, v and w are just arbitrary constants. Now, the question is, what is the state of the first two qubits if the third is measured to be |1>?

2. Relevant equations

3. The attempt at a solution

Do I have to use some sort of properties of product states and entangled states, can someone please help? I don't really know how to approach this problem.